/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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/*
 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - All Rights Reserved
 *
 *   The original version of this source code and documentation is copyrighted
 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
 * materials are provided under terms of a License Agreement between Taligent
 * and Sun. This technology is protected by multiple US and International
 * patents. This notice and attribution to Taligent may not be removed.
 *   Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.text;

/**
 * <code>FieldPosition</code> is a simple class used by <code>Format</code>
 * and its subclasses to identify fields in formatted output. Fields can
 * be identified in two ways:
 * <ul>
 * <li>By an integer constant, whose names typically end with
 * <code>_FIELD</code>. The constants are defined in the various
 * subclasses of <code>Format</code>.
 * <li>By a <code>Format.Field</code> constant, see <code>ERA_FIELD</code>
 * and its friends in <code>DateFormat</code> for an example.
 * </ul>
 * <p>
 * <code>FieldPosition</code> keeps track of the position of the
 * field within the formatted output with two indices: the index
 * of the first character of the field and the index of the last
 * character of the field.
 *
 * <p>
 * One version of the <code>format</code> method in the various
 * <code>Format</code> classes requires a <code>FieldPosition</code>
 * object as an argument. You use this <code>format</code> method
 * to perform partial formatting or to get information about the
 * formatted output (such as the position of a field).
 *
 * <p>
 * If you are interested in the positions of all attributes in the
 * formatted string use the <code>Format</code> method
 * <code>formatToCharacterIterator</code>.
 *
 * @author Mark Davis
 * @see java.text.Format
 */
public class FieldPosition {

  /**
   * Input: Desired field to determine start and end offsets for.
   * The meaning depends on the subclass of Format.
   */
  int field = 0;

  /**
   * Output: End offset of field in text.
   * If the field does not occur in the text, 0 is returned.
   */
  int endIndex = 0;

  /**
   * Output: Start offset of field in text.
   * If the field does not occur in the text, 0 is returned.
   */
  int beginIndex = 0;

  /**
   * Desired field this FieldPosition is for.
   */
  private Format.Field attribute;

  /**
   * Creates a FieldPosition object for the given field.  Fields are
   * identified by constants, whose names typically end with _FIELD,
   * in the various subclasses of Format.
   *
   * @param field the field identifier
   * @see java.text.NumberFormat#INTEGER_FIELD
   * @see java.text.NumberFormat#FRACTION_FIELD
   * @see java.text.DateFormat#YEAR_FIELD
   * @see java.text.DateFormat#MONTH_FIELD
   */
  public FieldPosition(int field) {
    this.field = field;
  }

  /**
   * Creates a FieldPosition object for the given field constant. Fields are
   * identified by constants defined in the various <code>Format</code>
   * subclasses. This is equivalent to calling
   * <code>new FieldPosition(attribute, -1)</code>.
   *
   * @param attribute Format.Field constant identifying a field
   * @since 1.4
   */
  public FieldPosition(Format.Field attribute) {
    this(attribute, -1);
  }

  /**
   * Creates a <code>FieldPosition</code> object for the given field.
   * The field is identified by an attribute constant from one of the
   * <code>Field</code> subclasses as well as an integer field ID
   * defined by the <code>Format</code> subclasses. <code>Format</code>
   * subclasses that are aware of <code>Field</code> should give precedence
   * to <code>attribute</code> and ignore <code>fieldID</code> if
   * <code>attribute</code> is not null. However, older <code>Format</code>
   * subclasses may not be aware of <code>Field</code> and rely on
   * <code>fieldID</code>. If the field has no corresponding integer
   * constant, <code>fieldID</code> should be -1.
   *
   * @param attribute Format.Field constant identifying a field
   * @param fieldID integer constant identifying a field
   * @since 1.4
   */
  public FieldPosition(Format.Field attribute, int fieldID) {
    this.attribute = attribute;
    this.field = fieldID;
  }

  /**
   * Returns the field identifier as an attribute constant
   * from one of the <code>Field</code> subclasses. May return null if
   * the field is specified only by an integer field ID.
   *
   * @return Identifier for the field
   * @since 1.4
   */
  public Format.Field getFieldAttribute() {
    return attribute;
  }

  /**
   * Retrieves the field identifier.
   *
   * @return the field identifier
   */
  public int getField() {
    return field;
  }

  /**
   * Retrieves the index of the first character in the requested field.
   *
   * @return the begin index
   */
  public int getBeginIndex() {
    return beginIndex;
  }

  /**
   * Retrieves the index of the character following the last character in the
   * requested field.
   *
   * @return the end index
   */
  public int getEndIndex() {
    return endIndex;
  }

  /**
   * Sets the begin index.  For use by subclasses of Format.
   *
   * @param bi the begin index
   * @since 1.2
   */
  public void setBeginIndex(int bi) {
    beginIndex = bi;
  }

  /**
   * Sets the end index.  For use by subclasses of Format.
   *
   * @param ei the end index
   * @since 1.2
   */
  public void setEndIndex(int ei) {
    endIndex = ei;
  }

  /**
   * Returns a <code>Format.FieldDelegate</code> instance that is associated
   * with the FieldPosition. When the delegate is notified of the same
   * field the FieldPosition is associated with, the begin/end will be
   * adjusted.
   */
  Format.FieldDelegate getFieldDelegate() {
    return new Delegate();
  }

  /**
   * Overrides equals
   */
  public boolean equals(Object obj) {
    if (obj == null) {
      return false;
    }
    if (!(obj instanceof FieldPosition)) {
      return false;
    }
    FieldPosition other = (FieldPosition) obj;
    if (attribute == null) {
      if (other.attribute != null) {
        return false;
      }
    } else if (!attribute.equals(other.attribute)) {
      return false;
    }
    return (beginIndex == other.beginIndex
        && endIndex == other.endIndex
        && field == other.field);
  }

  /**
   * Returns a hash code for this FieldPosition.
   *
   * @return a hash code value for this object
   */
  public int hashCode() {
    return (field << 24) | (beginIndex << 16) | endIndex;
  }

  /**
   * Return a string representation of this FieldPosition.
   *
   * @return a string representation of this object
   */
  public String toString() {
    return getClass().getName() +
        "[field=" + field + ",attribute=" + attribute +
        ",beginIndex=" + beginIndex +
        ",endIndex=" + endIndex + ']';
  }


  /**
   * Return true if the receiver wants a <code>Format.Field</code> value and
   * <code>attribute</code> is equal to it.
   */
  private boolean matchesField(Format.Field attribute) {
    if (this.attribute != null) {
      return this.attribute.equals(attribute);
    }
    return false;
  }

  /**
   * Return true if the receiver wants a <code>Format.Field</code> value and
   * <code>attribute</code> is equal to it, or true if the receiver
   * represents an inteter constant and <code>field</code> equals it.
   */
  private boolean matchesField(Format.Field attribute, int field) {
    if (this.attribute != null) {
      return this.attribute.equals(attribute);
    }
    return (field == this.field);
  }


  /**
   * An implementation of FieldDelegate that will adjust the begin/end
   * of the FieldPosition if the arguments match the field of
   * the FieldPosition.
   */
  private class Delegate implements Format.FieldDelegate {

    /**
     * Indicates whether the field has been  encountered before. If this
     * is true, and <code>formatted</code> is invoked, the begin/end
     * are not updated.
     */
    private boolean encounteredField;

    public void formatted(Format.Field attr, Object value, int start,
        int end, StringBuffer buffer) {
      if (!encounteredField && matchesField(attr)) {
        setBeginIndex(start);
        setEndIndex(end);
        encounteredField = (start != end);
      }
    }

    public void formatted(int fieldID, Format.Field attr, Object value,
        int start, int end, StringBuffer buffer) {
      if (!encounteredField && matchesField(attr, fieldID)) {
        setBeginIndex(start);
        setEndIndex(end);
        encounteredField = (start != end);
      }
    }
  }
}
